[linux-block.git] / mm / kasan / quarantine.c

// SPDX-License-Identifier: GPL-2.0
/*
 * KASAN quarantine.
 *
 * Author: Alexander Potapenko <glider@google.com>
 * Copyright (C) 2016 Google, Inc.
 *
 * Based on code by Dmitry Chernenkov.
 */

#include <linux/gfp.h>
#include <linux/hash.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/printk.h>
#include <linux/shrinker.h>
#include <linux/slab.h>
#include <linux/srcu.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/cpuhotplug.h>

#include "../slab.h"
#include "kasan.h"

/* Data structure and operations for quarantine queues. */

/*
 * Each queue is a signle-linked list, which also stores the total size of
 * objects inside of it.
 */
struct qlist_head {
	struct qlist_node *head;
	struct qlist_node *tail;
	size_t bytes;
	bool offline;
};

#define QLIST_INIT { NULL, NULL, 0 }

static bool qlist_empty(struct qlist_head *q)
{
	return !q->head;
}

static void qlist_init(struct qlist_head *q)
{
	q->head = q->tail = NULL;
	q->bytes = 0;
}

static void qlist_put(struct qlist_head *q, struct qlist_node *qlink,
		size_t size)
{
	if (unlikely(qlist_empty(q)))
		q->head = qlink;
	else
		q->tail->next = qlink;
	q->tail = qlink;
	qlink->next = NULL;
	q->bytes += size;
}

static void qlist_move_all(struct qlist_head *from, struct qlist_head *to)
{
	if (unlikely(qlist_empty(from)))
		return;

	if (qlist_empty(to)) {
		*to = *from;
		qlist_init(from);
		return;
	}

	to->tail->next = from->head;
	to->tail = from->tail;
	to->bytes += from->bytes;

	qlist_init(from);
}

#define QUARANTINE_PERCPU_SIZE (1 << 20)
#define QUARANTINE_BATCHES \
	(1024 > 4 * CONFIG_NR_CPUS ? 1024 : 4 * CONFIG_NR_CPUS)

/*
 * The object quarantine consists of per-cpu queues and a global queue,
 * guarded by quarantine_lock.
 */
static DEFINE_PER_CPU(struct qlist_head, cpu_quarantine);

/* Round-robin FIFO array of batches. */
static struct qlist_head global_quarantine[QUARANTINE_BATCHES];
static int quarantine_head;
static int quarantine_tail;
/* Total size of all objects in global_quarantine across all batches. */
static unsigned long quarantine_size;
static DEFINE_RAW_SPINLOCK(quarantine_lock);
DEFINE_STATIC_SRCU(remove_cache_srcu);

/* Maximum size of the global queue. */
static unsigned long quarantine_max_size;

/*
 * Target size of a batch in global_quarantine.
 * Usually equal to QUARANTINE_PERCPU_SIZE unless we have too much RAM.
 */
static unsigned long quarantine_batch_size;

/*
 * The fraction of physical memory the quarantine is allowed to occupy.
 * Quarantine doesn't support memory shrinker with SLAB allocator, so we keep
 * the ratio low to avoid OOM.
 */
#define QUARANTINE_FRACTION 32

static struct kmem_cache *qlink_to_cache(struct qlist_node *qlink)
{
	return virt_to_head_page(qlink)->slab_cache;
}

static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
{
	struct kasan_free_meta *free_info =
		container_of(qlink, struct kasan_free_meta,
			     quarantine_link);

	return ((void *)free_info) - cache->kasan_info.free_meta_offset;
}

static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
{
	void *object = qlink_to_object(qlink, cache);
	unsigned long flags;

	if (IS_ENABLED(CONFIG_SLAB))
		local_irq_save(flags);

	/*
	 * As the object now gets freed from the quaratine, assume that its
	 * free track is no longer valid.
	 */
	*(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREE;

	___cache_free(cache, object, _THIS_IP_);

	if (IS_ENABLED(CONFIG_SLAB))
		local_irq_restore(flags);
}

static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache)
{
	struct qlist_node *qlink;

	if (unlikely(qlist_empty(q)))
		return;

	qlink = q->head;
	while (qlink) {
		struct kmem_cache *obj_cache =
			cache ? cache :	qlink_to_cache(qlink);
		struct qlist_node *next = qlink->next;

		qlink_free(qlink, obj_cache);
		qlink = next;
	}
	qlist_init(q);
}

bool kasan_quarantine_put(struct kmem_cache *cache, void *object)
{
	unsigned long flags;
	struct qlist_head *q;
	struct qlist_head temp = QLIST_INIT;
	struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);

	/*
	 * If there's no metadata for this object, don't put it into
	 * quarantine.
	 */
	if (!meta)
		return false;

	/*
	 * Note: irq must be disabled until after we move the batch to the
	 * global quarantine. Otherwise kasan_quarantine_remove_cache() can
	 * miss some objects belonging to the cache if they are in our local
	 * temp list. kasan_quarantine_remove_cache() executes on_each_cpu()
	 * at the beginning which ensures that it either sees the objects in
	 * per-cpu lists or in the global quarantine.
	 */
	local_irq_save(flags);

	q = this_cpu_ptr(&cpu_quarantine);
	if (q->offline) {
		local_irq_restore(flags);
		return false;
	}
	qlist_put(q, &meta->quarantine_link, cache->size);
	if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) {
		qlist_move_all(q, &temp);

		raw_spin_lock(&quarantine_lock);
		WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes);
		qlist_move_all(&temp, &global_quarantine[quarantine_tail]);
		if (global_quarantine[quarantine_tail].bytes >=
				READ_ONCE(quarantine_batch_size)) {
			int new_tail;

			new_tail = quarantine_tail + 1;
			if (new_tail == QUARANTINE_BATCHES)
				new_tail = 0;
			if (new_tail != quarantine_head)
				quarantine_tail = new_tail;
		}
		raw_spin_unlock(&quarantine_lock);
	}

	local_irq_restore(flags);

	return true;
}

void kasan_quarantine_reduce(void)
{
	size_t total_size, new_quarantine_size, percpu_quarantines;
	unsigned long flags;
	int srcu_idx;
	struct qlist_head to_free = QLIST_INIT;

	if (likely(READ_ONCE(quarantine_size) <=
		   READ_ONCE(quarantine_max_size)))
		return;

	/*
	 * srcu critical section ensures that kasan_quarantine_remove_cache()
	 * will not miss objects belonging to the cache while they are in our
	 * local to_free list. srcu is chosen because (1) it gives us private
	 * grace period domain that does not interfere with anything else,
	 * and (2) it allows synchronize_srcu() to return without waiting
	 * if there are no pending read critical sections (which is the
	 * expected case).
	 */
	srcu_idx = srcu_read_lock(&remove_cache_srcu);
	raw_spin_lock_irqsave(&quarantine_lock, flags);

	/*
	 * Update quarantine size in case of hotplug. Allocate a fraction of
	 * the installed memory to quarantine minus per-cpu queue limits.
	 */
	total_size = (totalram_pages() << PAGE_SHIFT) /
		QUARANTINE_FRACTION;
	percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus();
	new_quarantine_size = (total_size < percpu_quarantines) ?
		0 : total_size - percpu_quarantines;
	WRITE_ONCE(quarantine_max_size, new_quarantine_size);
	/* Aim at consuming at most 1/2 of slots in quarantine. */
	WRITE_ONCE(quarantine_batch_size, max((size_t)QUARANTINE_PERCPU_SIZE,
		2 * total_size / QUARANTINE_BATCHES));

	if (likely(quarantine_size > quarantine_max_size)) {
		qlist_move_all(&global_quarantine[quarantine_head], &to_free);
		WRITE_ONCE(quarantine_size, quarantine_size - to_free.bytes);
		quarantine_head++;
		if (quarantine_head == QUARANTINE_BATCHES)
			quarantine_head = 0;
	}

	raw_spin_unlock_irqrestore(&quarantine_lock, flags);

	qlist_free_all(&to_free, NULL);
	srcu_read_unlock(&remove_cache_srcu, srcu_idx);
}

static void qlist_move_cache(struct qlist_head *from,
				   struct qlist_head *to,
				   struct kmem_cache *cache)
{
	struct qlist_node *curr;

	if (unlikely(qlist_empty(from)))
		return;

	curr = from->head;
	qlist_init(from);
	while (curr) {
		struct qlist_node *next = curr->next;
		struct kmem_cache *obj_cache = qlink_to_cache(curr);

		if (obj_cache == cache)
			qlist_put(to, curr, obj_cache->size);
		else
			qlist_put(from, curr, obj_cache->size);

		curr = next;
	}
}

static void per_cpu_remove_cache(void *arg)
{
	struct kmem_cache *cache = arg;
	struct qlist_head to_free = QLIST_INIT;
	struct qlist_head *q;

	q = this_cpu_ptr(&cpu_quarantine);
	qlist_move_cache(q, &to_free, cache);
	qlist_free_all(&to_free, cache);
}

/* Free all quarantined objects belonging to cache. */
void kasan_quarantine_remove_cache(struct kmem_cache *cache)
{
	unsigned long flags, i;
	struct qlist_head to_free = QLIST_INIT;

	/*
	 * Must be careful to not miss any objects that are being moved from
	 * per-cpu list to the global quarantine in kasan_quarantine_put(),
	 * nor objects being freed in kasan_quarantine_reduce(). on_each_cpu()
	 * achieves the first goal, while synchronize_srcu() achieves the
	 * second.
	 */
	on_each_cpu(per_cpu_remove_cache, cache, 1);

	raw_spin_lock_irqsave(&quarantine_lock, flags);
	for (i = 0; i < QUARANTINE_BATCHES; i++) {
		if (qlist_empty(&global_quarantine[i]))
			continue;
		qlist_move_cache(&global_quarantine[i], &to_free, cache);
		/* Scanning whole quarantine can take a while. */
		raw_spin_unlock_irqrestore(&quarantine_lock, flags);
		cond_resched();
		raw_spin_lock_irqsave(&quarantine_lock, flags);
	}
	raw_spin_unlock_irqrestore(&quarantine_lock, flags);

	qlist_free_all(&to_free, cache);

	synchronize_srcu(&remove_cache_srcu);
}

static int kasan_cpu_online(unsigned int cpu)
{
	this_cpu_ptr(&cpu_quarantine)->offline = false;
	return 0;
}

static int kasan_cpu_offline(unsigned int cpu)
{
	struct qlist_head *q;

	q = this_cpu_ptr(&cpu_quarantine);
	/* Ensure the ordering between the writing to q->offline and
	 * qlist_free_all. Otherwise, cpu_quarantine may be corrupted
	 * by interrupt.
	 */
	WRITE_ONCE(q->offline, true);
	barrier();
	qlist_free_all(q, NULL);
	return 0;
}

static int __init kasan_cpu_quarantine_init(void)
{
	int ret = 0;

	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mm/kasan:online",
				kasan_cpu_online, kasan_cpu_offline);
	if (ret < 0)
		pr_err("kasan cpu quarantine register failed [%d]\n", ret);
	return ret;
}
late_initcall(kasan_cpu_quarantine_init);
Commit	Line	Data
e886bf9d	1	// SPDX-License-Identifier: GPL-2.0
55834c59 AP	2	/*
	3	* KASAN quarantine.
	4	*
	5	* Author: Alexander Potapenko <glider@google.com>
	6	* Copyright (C) 2016 Google, Inc.
	7	*
	8	* Based on code by Dmitry Chernenkov.
55834c59 AP	9	*/
	10
	11	#include <linux/gfp.h>
	12	#include <linux/hash.h>
	13	#include <linux/kernel.h>
	14	#include <linux/mm.h>
	15	#include <linux/percpu.h>
	16	#include <linux/printk.h>
	17	#include <linux/shrinker.h>
	18	#include <linux/slab.h>
ce5bec54	19	#include <linux/srcu.h>
55834c59 AP	20	#include <linux/string.h>
55834c59 AP	21	#include <linux/types.h>
6c82d45c	22	#include <linux/cpuhotplug.h>
55834c59 AP	23
	24	#include "../slab.h"
	25	#include "kasan.h"
	26
	27	/* Data structure and operations for quarantine queues. */
	28
	29	/*
	30	* Each queue is a signle-linked list, which also stores the total size of
	31	* objects inside of it.
	32	*/
	33	struct qlist_head {
	34	struct qlist_node *head;
	35	struct qlist_node *tail;
	36	size_t bytes;
6c82d45c	37	bool offline;
55834c59 AP	38	};
	39
	40	#define QLIST_INIT { NULL, NULL, 0 }
	41
	42	static bool qlist_empty(struct qlist_head *q)
	43	{
	44	return !q->head;
	45	}
	46
	47	static void qlist_init(struct qlist_head *q)
	48	{
	49	q->head = q->tail = NULL;
	50	q->bytes = 0;
	51	}
	52
	53	static void qlist_put(struct qlist_head q, struct qlist_node qlink,
	54	size_t size)
	55	{
	56	if (unlikely(qlist_empty(q)))
	57	q->head = qlink;
	58	else
	59	q->tail->next = qlink;
	60	q->tail = qlink;
	61	qlink->next = NULL;
	62	q->bytes += size;
	63	}
	64
	65	static void qlist_move_all(struct qlist_head from, struct qlist_head to)
	66	{
	67	if (unlikely(qlist_empty(from)))
	68	return;
	69
	70	if (qlist_empty(to)) {
	71	to = from;
	72	qlist_init(from);
	73	return;
	74	}
	75
	76	to->tail->next = from->head;
	77	to->tail = from->tail;
	78	to->bytes += from->bytes;
	79
	80	qlist_init(from);
	81	}
	82
64abdcb2 DV	83	#define QUARANTINE_PERCPU_SIZE (1 << 20)
	84	#define QUARANTINE_BATCHES \
	85	(1024 > 4 * CONFIG_NR_CPUS ? 1024 : 4 * CONFIG_NR_CPUS)
55834c59 AP	86
	87	/*
	88	* The object quarantine consists of per-cpu queues and a global queue,
	89	* guarded by quarantine_lock.
	90	*/
	91	static DEFINE_PER_CPU(struct qlist_head, cpu_quarantine);
	92
64abdcb2 DV	93	/* Round-robin FIFO array of batches. */
	94	static struct qlist_head global_quarantine[QUARANTINE_BATCHES];
	95	static int quarantine_head;
	96	static int quarantine_tail;
	97	/* Total size of all objects in global_quarantine across all batches. */
	98	static unsigned long quarantine_size;
026d1eaf	99	static DEFINE_RAW_SPINLOCK(quarantine_lock);
ce5bec54	100	DEFINE_STATIC_SRCU(remove_cache_srcu);
55834c59 AP	101
55834c59 AP	102	/* Maximum size of the global queue. */
64abdcb2 DV	103	static unsigned long quarantine_max_size;
	104
	105	/*
	106	* Target size of a batch in global_quarantine.
	107	* Usually equal to QUARANTINE_PERCPU_SIZE unless we have too much RAM.
	108	*/
	109	static unsigned long quarantine_batch_size;
55834c59 AP	110
	111	/*
	112	* The fraction of physical memory the quarantine is allowed to occupy.
	113	* Quarantine doesn't support memory shrinker with SLAB allocator, so we keep
	114	* the ratio low to avoid OOM.
	115	*/
	116	#define QUARANTINE_FRACTION 32
	117
55834c59 AP	118	static struct kmem_cache qlink_to_cache(struct qlist_node qlink)
	119	{
	120	return virt_to_head_page(qlink)->slab_cache;
	121	}
	122
	123	static void qlink_to_object(struct qlist_node qlink, struct kmem_cache *cache)
	124	{
	125	struct kasan_free_meta *free_info =
	126	container_of(qlink, struct kasan_free_meta,
	127	quarantine_link);
	128
	129	return ((void *)free_info) - cache->kasan_info.free_meta_offset;
	130	}
	131
	132	static void qlink_free(struct qlist_node qlink, struct kmem_cache cache)
	133	{
	134	void *object = qlink_to_object(qlink, cache);
55834c59 AP	135	unsigned long flags;
55834c59 AP	136
f7376aed AR	137	if (IS_ENABLED(CONFIG_SLAB))
	138	local_irq_save(flags);
	139
97593cad AK	140	/*
	141	* As the object now gets freed from the quaratine, assume that its
	142	* free track is no longer valid.
	143	*/
e4b7818b	144	(u8 )kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREE;
97593cad	145
55834c59	146	___cache_free(cache, object, _THIS_IP_);
f7376aed AR	147
	148	if (IS_ENABLED(CONFIG_SLAB))
	149	local_irq_restore(flags);
55834c59 AP	150	}
	151
	152	static void qlist_free_all(struct qlist_head q, struct kmem_cache cache)
	153	{
	154	struct qlist_node *qlink;
	155
	156	if (unlikely(qlist_empty(q)))
	157	return;
	158
	159	qlink = q->head;
	160	while (qlink) {
	161	struct kmem_cache *obj_cache =
	162	cache ? cache : qlink_to_cache(qlink);
	163	struct qlist_node *next = qlink->next;
	164
	165	qlink_free(qlink, obj_cache);
	166	qlink = next;
	167	}
	168	qlist_init(q);
	169	}
	170
f00748bf	171	bool kasan_quarantine_put(struct kmem_cache cache, void object)
55834c59 AP	172	{
	173	unsigned long flags;
	174	struct qlist_head *q;
	175	struct qlist_head temp = QLIST_INIT;
6476792f	176	struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);
55834c59	177
97593cad AK	178	/*
	179	* If there's no metadata for this object, don't put it into
	180	* quarantine.
	181	*/
	182	if (!meta)
	183	return false;
	184
ce5bec54 DV	185	/*
ce5bec54 DV	186	* Note: irq must be disabled until after we move the batch to the
f00748bf AK	187	* global quarantine. Otherwise kasan_quarantine_remove_cache() can
	188	* miss some objects belonging to the cache if they are in our local
	189	* temp list. kasan_quarantine_remove_cache() executes on_each_cpu()
	190	* at the beginning which ensures that it either sees the objects in
	191	* per-cpu lists or in the global quarantine.
ce5bec54	192	*/
55834c59 AP	193	local_irq_save(flags);
	194
	195	q = this_cpu_ptr(&cpu_quarantine);
6c82d45c KYL	196	if (q->offline) {
6c82d45c KYL	197	local_irq_restore(flags);
97593cad	198	return false;
6c82d45c	199	}
6476792f	200	qlist_put(q, &meta->quarantine_link, cache->size);
ce5bec54	201	if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) {
55834c59 AP	202	qlist_move_all(q, &temp);
55834c59 AP	203
026d1eaf	204	raw_spin_lock(&quarantine_lock);
64abdcb2 DV	205	WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes);
	206	qlist_move_all(&temp, &global_quarantine[quarantine_tail]);
	207	if (global_quarantine[quarantine_tail].bytes >=
	208	READ_ONCE(quarantine_batch_size)) {
	209	int new_tail;
	210
	211	new_tail = quarantine_tail + 1;
	212	if (new_tail == QUARANTINE_BATCHES)
	213	new_tail = 0;
	214	if (new_tail != quarantine_head)
	215	quarantine_tail = new_tail;
	216	}
026d1eaf	217	raw_spin_unlock(&quarantine_lock);
55834c59	218	}
ce5bec54 DV	219
ce5bec54 DV	220	local_irq_restore(flags);
97593cad AK	221
97593cad AK	222	return true;
55834c59 AP	223	}
55834c59 AP	224
f00748bf	225	void kasan_quarantine_reduce(void)
55834c59	226	{
64abdcb2	227	size_t total_size, new_quarantine_size, percpu_quarantines;
55834c59	228	unsigned long flags;
ce5bec54	229	int srcu_idx;
55834c59	230	struct qlist_head to_free = QLIST_INIT;
55834c59	231
64abdcb2 DV	232	if (likely(READ_ONCE(quarantine_size) <=
64abdcb2 DV	233	READ_ONCE(quarantine_max_size)))
55834c59 AP	234	return;
55834c59 AP	235
ce5bec54	236	/*
f00748bf	237	* srcu critical section ensures that kasan_quarantine_remove_cache()
ce5bec54 DV	238	* will not miss objects belonging to the cache while they are in our
	239	* local to_free list. srcu is chosen because (1) it gives us private
	240	* grace period domain that does not interfere with anything else,
	241	* and (2) it allows synchronize_srcu() to return without waiting
	242	* if there are no pending read critical sections (which is the
	243	* expected case).
	244	*/
	245	srcu_idx = srcu_read_lock(&remove_cache_srcu);
026d1eaf	246	raw_spin_lock_irqsave(&quarantine_lock, flags);
55834c59 AP	247
	248	/*
	249	* Update quarantine size in case of hotplug. Allocate a fraction of
	250	* the installed memory to quarantine minus per-cpu queue limits.
	251	*/
ca79b0c2	252	total_size = (totalram_pages() << PAGE_SHIFT) /
55834c59	253	QUARANTINE_FRACTION;
c3cee372	254	percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus();
64abdcb2 DV	255	new_quarantine_size = (total_size < percpu_quarantines) ?
	256	0 : total_size - percpu_quarantines;
	257	WRITE_ONCE(quarantine_max_size, new_quarantine_size);
	258	/* Aim at consuming at most 1/2 of slots in quarantine. */
	259	WRITE_ONCE(quarantine_batch_size, max((size_t)QUARANTINE_PERCPU_SIZE,
	260	2 * total_size / QUARANTINE_BATCHES));
	261
	262	if (likely(quarantine_size > quarantine_max_size)) {
	263	qlist_move_all(&global_quarantine[quarantine_head], &to_free);
	264	WRITE_ONCE(quarantine_size, quarantine_size - to_free.bytes);
	265	quarantine_head++;
	266	if (quarantine_head == QUARANTINE_BATCHES)
	267	quarantine_head = 0;
55834c59	268	}
55834c59	269
026d1eaf	270	raw_spin_unlock_irqrestore(&quarantine_lock, flags);
55834c59 AP	271
55834c59 AP	272	qlist_free_all(&to_free, NULL);
ce5bec54	273	srcu_read_unlock(&remove_cache_srcu, srcu_idx);
55834c59 AP	274	}
	275
	276	static void qlist_move_cache(struct qlist_head *from,
	277	struct qlist_head *to,
	278	struct kmem_cache *cache)
	279	{
0ab686d8	280	struct qlist_node *curr;
55834c59 AP	281
	282	if (unlikely(qlist_empty(from)))
	283	return;
	284
	285	curr = from->head;
0ab686d8	286	qlist_init(from);
55834c59	287	while (curr) {
0ab686d8 JK	288	struct qlist_node *next = curr->next;
	289	struct kmem_cache *obj_cache = qlink_to_cache(curr);
	290
	291	if (obj_cache == cache)
	292	qlist_put(to, curr, obj_cache->size);
	293	else
	294	qlist_put(from, curr, obj_cache->size);
	295
	296	curr = next;
55834c59 AP	297	}
	298	}
	299
	300	static void per_cpu_remove_cache(void *arg)
	301	{
	302	struct kmem_cache *cache = arg;
	303	struct qlist_head to_free = QLIST_INIT;
	304	struct qlist_head *q;
	305
	306	q = this_cpu_ptr(&cpu_quarantine);
	307	qlist_move_cache(q, &to_free, cache);
	308	qlist_free_all(&to_free, cache);
	309	}
	310
f9fa1d91	311	/* Free all quarantined objects belonging to cache. */
f00748bf	312	void kasan_quarantine_remove_cache(struct kmem_cache *cache)
55834c59	313	{
64abdcb2	314	unsigned long flags, i;
55834c59 AP	315	struct qlist_head to_free = QLIST_INIT;
55834c59 AP	316
ce5bec54 DV	317	/*
ce5bec54 DV	318	* Must be careful to not miss any objects that are being moved from
f00748bf AK	319	* per-cpu list to the global quarantine in kasan_quarantine_put(),
f00748bf AK	320	* nor objects being freed in kasan_quarantine_reduce(). on_each_cpu()
ce5bec54 DV	321	* achieves the first goal, while synchronize_srcu() achieves the
	322	* second.
	323	*/
55834c59 AP	324	on_each_cpu(per_cpu_remove_cache, cache, 1);
55834c59 AP	325
026d1eaf	326	raw_spin_lock_irqsave(&quarantine_lock, flags);
68fd814a DV	327	for (i = 0; i < QUARANTINE_BATCHES; i++) {
	328	if (qlist_empty(&global_quarantine[i]))
	329	continue;
64abdcb2	330	qlist_move_cache(&global_quarantine[i], &to_free, cache);
68fd814a	331	/* Scanning whole quarantine can take a while. */
026d1eaf	332	raw_spin_unlock_irqrestore(&quarantine_lock, flags);
68fd814a	333	cond_resched();
026d1eaf	334	raw_spin_lock_irqsave(&quarantine_lock, flags);
68fd814a	335	}
026d1eaf	336	raw_spin_unlock_irqrestore(&quarantine_lock, flags);
55834c59 AP	337
55834c59 AP	338	qlist_free_all(&to_free, cache);
ce5bec54 DV	339
ce5bec54 DV	340	synchronize_srcu(&remove_cache_srcu);
55834c59	341	}
6c82d45c KYL	342
	343	static int kasan_cpu_online(unsigned int cpu)
	344	{
	345	this_cpu_ptr(&cpu_quarantine)->offline = false;
	346	return 0;
	347	}
	348
	349	static int kasan_cpu_offline(unsigned int cpu)
	350	{
	351	struct qlist_head *q;
	352
	353	q = this_cpu_ptr(&cpu_quarantine);
	354	/* Ensure the ordering between the writing to q->offline and
	355	* qlist_free_all. Otherwise, cpu_quarantine may be corrupted
	356	* by interrupt.
	357	*/
	358	WRITE_ONCE(q->offline, true);
	359	barrier();
	360	qlist_free_all(q, NULL);
	361	return 0;
	362	}
	363
	364	static int __init kasan_cpu_quarantine_init(void)
	365	{
	366	int ret = 0;
	367
	368	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mm/kasan:online",
	369	kasan_cpu_online, kasan_cpu_offline);
	370	if (ret < 0)
	371	pr_err("kasan cpu quarantine register failed [%d]\n", ret);
	372	return ret;
	373	}
	374	late_initcall(kasan_cpu_quarantine_init);